1. Field of the Invention
The present disclosure relates to a power transmission device for a vacuum interrupter applied to a vacuum circuit breaker, and a vacuum breaker having the same.
2. Background of the Invention
Generally, a vacuum interrupter of a vacuum circuit breaker is a main extinguishing device applied to a vacuum breaker, a vacuum switching device, a vacuum connector, etc. for interrupting a load current or an accident current in a power system. The vacuum circuit breaker for controlling power transmission and protecting a power system has advantages such as a large interruption capacity, high reliability, high stability, and small installation space. Owing to such advantages the application ranges of the vacuum circuit breaker are increased. Furthermore, as industrial equipment becomes large, an interruption capacity of the circuit breaker becomes also large.
In case of an ultra high voltage vacuum interrupter, an interval between a fixed electrode and a movable electrode in a trip state is wider than that of a low voltage vacuum interrupter, and a closing speed is very rapid. Accordingly, an impact amount between the movable electrode and the fixed electrode during a closing operation is very great. Such impact may cause transformation of a fixed electrode and a movable electrode, and such transformation may lower performance of the vacuum interrupter. In order to solve such problems, if the entire closing speed is made to be slow, closing time becomes long. As a result, time for which a pre-arc occurring when a vacuum insulation state disappears during a closing operation is maintained is long. Such long duration for which pre-arc has occurred badly influences on performance of the vacuum breaker. Therefore, the entire closing time should be constantly maintained.
FIG. 1 is a sectional view of a vacuum interrupter in accordance with the conventional art.
As shown in FIG. 1, the conventional vacuum interrupter includes an insulating container 1 sealed by a fixed side flange 2 and a movable side flange 3. A fixed electrode 4 and a movable electrode 5 face each other in a contactable manner in the insulating container 1, and are accommodated in an inner shield 6 fixed to the insulating container 1. A fixed shaft 4a of the fixed electrode 4 is fixedly-coupled to the fixed side flange 2, thereby being connected to the outside. And, a movable shaft 5a of the movable electrode 5 is slidably-coupled to the movable side flange 3, thereby being connected to an adjuster (not shown) disposed outside the insulating container by links and joints. Accordingly, movement of an output unit of the adjuster is proportional to movement of the movable shaft.
A bellows shield 7 is fixedly-coupled to the movable shaft 5a of the movable electrode 5, and a bellows 8 is provided between the bellows shield 7 and the movable side flange 3. Under such configuration, the movable electrode 5 and the movable shaft 5a are movably installed in the insulating container 1 in a sealed state.
In the conventional vacuum interrupter, in the occurrence of an accident current, the movable electrode moves, by the adjuster, towards a direction spaced from the fixed electrode. As a result, the movable electrode is separated from the fixed electrode, thereby extinguishing an accident current.
Once the accident current is extinguished, the movable electrode moves towards a closing direction by a restoration force of the adjuster, i.e., moves towards the fixed electrode at the same speed. As a result, the movable electrode comes in contact with the fixed electrode to implement a closing operation.
However, the conventional vacuum interrupter has the following problems.
Firstly, energy stored in a compression spring of the adjuster is applied to the movable electrode as it is. As a result, the movable electrode moves while maintaining the same speed during a closing operation, thereby having a significantly increased contact speed with the fixed electrode. This may increase an impact amount between the movable electrode and the fixed electrode, thereby causing damages of components of the movable electrode or the fixed electrode or the insulating container.